Life-history of No to thy las t 397 
mother-cells, and sometimes spore-tetrads and ripe spores 
(Fig. 18). The columella is always present, but much smaller 
than those of the larger sporogonia (Fig. 18), and its cells are 
distinguished from those of the archesporium with some diffi- 
culty, especially if the section is not straight and more deeply 
stained. In the case figured in Fig. 1 8, the cells of the colu- 
mella were little unlike those of the archesporium in regard to 
the contents of the cells. In all capsules examined, a colu- 
mella was found extending up through the centre of the 
capsule nearly to the apex, varying in size with that of the 
capsule. From the columella layers of sterile cells extend 
radially to the capsule-wall, dividing the spore-chamber into 
more or less irregular cavities in which lie, proceeding down- 
ward from the apex, spores, spore-tetrads and spore-mother- 
cells. By making rather thick longitudinal sections through 
a nearly mature capsule, and freeing the spores by tapping 
gently with the end of a camel’s-hair brush, one readily finds 
the columella with few sterile cells and spore-tetrads adhering 
(Fig. 21). The sterile cells fall out with the spores, and may 
be found scattered among them in the water. They are 
derived from the archesporium (Fig. 17). The capsule from 
which Fig. 17 was taken contained spores in its upper two- 
thirds : the columella is quite large, and the archesporium 
extends quite to the boundary between foot and capsule, 
where, in this case, the cells were just beginning to elongate 
preparatory to the separation of the capsule. In all robust 
and well-fed sporogonia (and many were examined) the cells 
of the archesporium were rich in protoplasm, staining deeply 
with alum-cochineal, and forming a sharp contrast to those of 
columella and capsule-wall. The structure of the mature 
capsule in the Anthoceroteae has been carefully described 
by Leitgeb 1 , so that further details need not be given here. 
The process of division in the spore-mother-cells, as far as 
observation went, agrees with that given by Strasburger for 
Anthoceros 2 . 
1 Loc. cit. 
2 Zellbildung und Zelltheilung. Third edition, p. 158, &c. (1880), 
